1. Field of the Invention
The invention relates to marine platforms such as for use in connection with undersea oil wells for example, and to pipelines such as for marine use for example.
2. Summary of the Invention
The invention provides in a tension leg platform having a buoyancy chamber anchored to the sea bed by means of tensioned legs, an anchoring arrangement for each leg comprising a pile driven into the sea bed, a chamber mounted on the pile and defining an orifice through which a said leg can extend into the chamber, and clamping means secured to the chamber and housed within the chamber, the clamping means clamping the leg to the chamber.
The invention further provides a pipe line for conveying a fluid from a first position to a second position, comprising a first tube extending from the first to the second position, a second tube extending from the first to the second position, the second tube lying inside the first tube and being arranged to feed fluid from the first to the second position, a valve coupled to the second tube at the first position to control the flow of fluid along the second tube, the valve being biased into a closed condition, means connected to the first tube to pressurise the first tube, and valve actuator means at the first position coupled to control the valve and connected to the first tube, the actuator means being operative in response to the pressure in the first tube exceeding a predetermined value to open the valve means against its bias.
The invention further provides a tension leg marine platform structure, comprising an air filled buoyancy chamber having an airlock, the airlock enabling access between the buoyancy chamber and a submersible craft when docked at the airlock, a deck, a plurality of columns supporting the deck on the chamber to lie above the level of the sea and providing access from the deck to the chamber, a plurality of tension legs each secured at one end to the buoyancy chamber, and a plurality of anchoring arrangements respectively for anchoring the other ends of the tension legs to the sea bed to hold the buoyancy chamber in a submerged state.
The invention further provides a tension leg marine platform structure, comprising an air filled buoyancy chamber having an airlock, the airlock enabling access between the buoyancy chamber and a submersible craft when docked at the airlock, a deck, a plurality of columns supporting the deck on the chamber to lie above the level of the sea and providing access from the deck to the chamber, a plurality of tension legs each secured at one end to the buoyancy chamber, and a plurality of anchoring arrangements respectively for anchoring the other ends of the tension legs to the sea bed to hold the buoyancy chamber in a submerged state.